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Table 1 Design features considered for assessment of risk of bias

From: Systematic reviews of observational studies of risk of thrombosis and bleeding in urological surgery (ROTBUS): introduction and methodology

Domain Lower risk of bias Higher risk of bias
Sampling and representativeness of the population Consecutive patient recruitment or administrative database with random sampling Non-consecutive patient recruitment or administrative database with non-random sampling
Study type International multicenter; multicenter in one country; single center, not single surgeon Single surgeon series
Source of information Data abstracted by investigators from patient charts Administrative database information
Thromboprophylaxis documentation Reporting of patients’ thromboprophylaxis No reporting of patients’ thromboprophylaxis
Diagnostic criteria Objective confirmation of symptomatic venous thromboembolism No objective confirmation of symptomatic venous thromboembolism
Loss to follow-up Less than 20% loss to follow-up 20% or more loss to follow-up